Risk assessment for epidemic spread of the quarantined potato pathogen Synchytrium endobioticum in the Republic of Georgia

Synchytrium endobioticum (causal agent of potato wart) is a devastating soilborne pathogen. Eradication is difficult and infestation can result in 100% yield loss, making this a strictly quarantined pathogen worldwide. Emerging epidemics pose a high risk to production in Georgia where potato is an essential staple, grown primarily by smallholder farmers, and yields are among the world’s lowest. S. endobioticum was first reported in Georgia in 2014 in a localized outbreak in Adjara. Because pathogen dissemination is primarily via human transport of infested tubers, understanding the local potato seed system is critical. This study was the first to systematically characterize the actors involved in seed and ware potato production and trade in Georgia. To collect this information, an expert elicitation was conducted in 2017 across a broad range of participants from the Georgian potato production sector. We present a model of the current potato seed exchange network for the most important agroecological regions. We integrated network analysis in a risk assessment for S. endobioticum spread in Georgia under 1) no intervention, 2) quarantine, 3) introduction of host plant resistance, and 4) combined quarantine and resistance deployment. Preliminary analyses suggest that under no intervention, risk of spread is high, while rapid and consistent quarantine can be effective. Methods presented here provide a general framework for future seed system risk assessments

Clinical and pathological observations on goats experimentally infected with Pseudomonas pseudomallei

The effects in goats of the subcutaneous injection of varying doses of Pseudomonas pseudomallei (90 to 500000 bacilli) suspended in normal saline are described. High doses ( more than or equal to 500 bacilli) caused acute, fatal infections. Lower doses (90 to 225 bacilli) caused acute or chronic disease when infection became established. However, 11 of 18 goats injected with the lower doses of bacilli showed no sign of infection on clinical or bacteriological examination. Response to antibiotic therapy with long acting tetracycline and chloramphenicol was minimum. Goats surviving the initial phase of infection tended to overcome the disease with a corresponding increase in the number of abscesses that were sterile at PM. In infected goats, clinical signs included undulating fever, wasting, anorexia, paresis of the hind legs, severe mastitis and abortion. PM examination revealed abscesses, predominantly in the spleen, lungs, subcutaneous injection site and its draining lymph node

Clinical and pathological observations on goats experimentally infected with Pseudomonas pseudomallei

The effects in goats of the subcutaneous injection of varying doses of Pseudomonas pseudomallei (90 to 500000 bacilli) suspended in normal saline are described. High doses ( more than or equal to 500 bacilli) caused acute, fatal infections. Lower doses (90 to 225 bacilli) caused acute or chronic disease when infection became established. However, 11 of 18 goats injected with the lower doses of bacilli showed no sign of infection on clinical or bacteriological examination. Response to antibiotic therapy with long acting tetracycline and chloramphenicol was minimum. Goats surviving the initial phase of infection tended to overcome the disease with a corresponding increase in the number of abscesses that were sterile at PM. In infected goats, clinical signs included undulating fever, wasting, anorexia, paresis of the hind legs, severe mastitis and abortion. PM examination revealed abscesses, predominantly in the spleen, lungs, subcutaneous injection site and its draining lymph node

An integrated seed health strategy and phytosanitary risk assessment: Potato in the Republic of Georgia

CONTEXT: Potato is an essential food staple and a critical crop for rural livelihoods in the Republic of Georgia, where many phytosanitary risks threaten production. OBJECTIVE: The objectives of this study were, first, to characterize the current seed and ware potato transaction network, value chain, varietal adoption, and phytosanitary risks for Georgia. Second, we modeled scenarios for the spread of an emerging pathogen, Synchytrium endobioticum, in Georgia as part of a geographic risk assessment analysis. Third, we coupled risk estimated in our simulation experiments with risk of reintroduction or invasion of pathogens via international trade or habitat connectivity. We found that a majority of seed potato is obtained from local sources in Georgia, and is of unknown phytosanitary quality

Where to Invest Project Efforts for Greater Benefit: A Framework for Management Performance Mapping with Examples for Potato Seed Health

Policymakers and donors often need to identify the locations where technologies are most likely to have important effects, to increase the benefits from agricultural development or extension efforts. Higher-quality information may help to target the high-benefit locations, but often actions are needed with limited information. The value of information (VOI) in this context is formalized by evaluating the results of decision making guided by a set of specific information compared with the results of acting without considering that information. We present a framework for management performance mapping that includes evaluating the VOI for decision making about geographic priorities in regional intervention strategies, in case studies of Andean and Kenyan potato seed systems. We illustrate the use of recursive partitioning, XGBoost, and Bayesian network models to characterize the relationships among seed health and yield responses and environmental and management predictors used in studies of seed degeneration. These analyses address the expected performance of an intervention based on geographic predictor variables. In the Andean example, positive selection of seed from asymptomatic plants was more effective at high altitudes in Ecuador. In the Kenyan example, there was the potential to target locations with higher technology adoption rates and with higher potato cropland connectivity, i.e., a likely more important role in regional epidemics. Targeting training to high management performance areas would often provide more benefits than would random selection of target areas. We illustrate how assessing the VOI can contribute to targeted development programs and support a culture of continuous improvement for interventions

Global cropland connectivity: A risk factor for invasion and saturation by emerging pathogens and pests

The geographic pattern of cropland is an important risk factor for invasion and saturation by crop-specific pathogens and arthropods. Understanding cropland networks supports smart pest sampling and mitigation strategies. We evaluate global networks of cropland connectivity for key vegetatively propagated crops (banana and plantain, cassava, potato, sweet potato, and yam) important for food security in the tropics. For each crop, potential movement between geographic location pairs was evaluated using a gravity model, with associated uncertainty quantification. The highly linked hub and bridge locations in cropland connectivity risk maps are likely priorities for surveillance and management, and for tracing intraregion movement of pathogens and pests. Important locations are identified beyond those locations that simply have high crop density. Cropland connectivity risk maps provide a new risk component for integration with other factors—such as climatic suitability, genetic resistance, and global trade routes—to inform pest risk assessment and mitigation